This application claims the benefit of JP 2000-003629 filed Jan. 12, 2000.
The present invention relates to an engine cooling air passage for construction equipment.
Recently, due to environmental sensitivity, equipment causing less noise to the environment (hereinafter called ambient noise) is demanded also in construction equipment. For this reason, conventionally, the front and the back, the left and the right side, and the top and the bottom of the entire bodies of an engine, a cooling fan and a radiator in front of the engine are covered with partition walls or wall surfaces of the other devices in such a manner as to be wrapped with them, and thereby an engine room is constructed. A cooling air inlet port is provided at an upper partition wall in front of the radiator of the engine room, and a cooling air exhaust port is provided at an upper partition wall at the back of the engine room to thereby form an engine cooling air passage, whereby cooling air is taken in from an upper front portion of the engine room and is discharged to an upper rear portion thereof. The structure in which noises of a cooling fan and an engine are not directly released outside according to the above configuration is generally achieved.
However, as for an engine cooling air passage for construction equipment, there always exists a demand for the solution to eliminate the contradictory phenomena in these three items: securing sufficient opening areas for the inlet port and the exhaust port to obtain sufficient amount of engine cooling air; the resultant increase in engine noise released to the outside; and increase in the size of the engine room to prevent the noise release.
The above problems the solution to which is demanded are explained below by separating them into the cooling air inlet port side and the cooling air exhaust port side.
(1) In the cooling air inlet port, the inlet port is provided in the upper partition wall in front of the radiator of the engine room, whereby the engine room is substantially extended in front of the radiator, which results in the increase in size and becomes a disadvantage to small-sized construction equipment. However, since a space in front of the radiator serves as a noise-suppressing duct, noise release from the inlet port can be reduced to the practical level. Further, for example, Japanese Utility Model Laid-open No. 3-64121 discloses the means for reducing the extension in front of the radiator by 50 percent to secure the inlet amount of cooling air, which proves effective.
(2) As for the cooling air exhaust port, the exhaust port can be easily provided in the upper partition wall at the back of the engine room without increasing the size of the engine room. However, this results in direct opening of the upper portion of the engine room, whereby engine noise, and the noises of a power transducer such as a hydraulic pump, for example, are directly released from the exhaust port without being attenuated, thus making it impossible to reduce the noise.
As is generally known, even if one of two equal sound sources (in this case, the cooling air inlet port and the cooling air exhaust port) is reduced to zero, the noise reduction effect of only about 3 dB is obtained if the other one remains as it is. Consequently, in the above situation, the noise reduction effect of the cooling air inlet port is buried, and construction equipment with less noise is not provided. Hence, it is one of important issues to form an engine cooling air passage in which discharge of sufficient amount of cooling air is compatible with sufficient reduction in noise release.
The above issue will be explained with FIG. 17 and FIG. 18.
FIG. 17 is a fragmentary perspective view of a hydraulic shovel having an engine room to which an engine cooling air passage according to a prior art is applied. In the hydraulic shovel, an upper revolving superstructure 2 is rotatably mounted at approximately a center of a top portion of the a base carrier 1, and at an upper rear end of the upper revolving superstructure 2, placed is a counterweight 3, in front of which, placed are an engine room 4, a hydraulic fluid tank 5 and a fuel tank 6. At a front part of the upper revolving superstructure 2, an operator""s cab 7 is placed at a left side, and a working machine 8 is attached at approximately a center portion. In a top face of the engine room 4, a cooling air inlet port 11 is provided at a left end portion of a vehicle body and a cooling air exhaust port 12 is provided at a right end portion of the vehicle body.
FIG. 18 is a fragmentary sectional top view of the engine room of FIG. 17, and FIG. 19 is a fragmentary sectional side view of the engine room. It should be noted that the broken line arrow represents a vector of a cooling fan blown-off air, while the solid line arrow represents a flow of a cooling air in FIGS. 18 and 19, and the same thing will apply hereinafter.
In FIGS. 18 and 19, entire bodies of an engine 13, an auxiliary pump 14, a hydraulic pump 15 as a power transducer, a cooling fan 16, a radiator 17, an oil cooler 18 and an air conditioning condenser 19 are covered with a front partition wall 21, a rear partition wall 22, a left side partition wall 23, a right side partition wall 24, an upper partition wall 25 and a lower partition wall 26 to define the engine room 4. The upper partition wall 25 is provided with the cooling air inlet port 11 in front of the radiator 17 and with the cooling air exhaust port 12 behind the engine 13.
In FIG. 18, in order to exhaust sufficient amount of cooling air, it is necessary to reduce exhaust resistance (hereinafter, called back pressure). The first problem regarding this is the following point. Normally, the vectors of blown-off air from the cooling fan 16 have the property that they have higher speed as they are away from the center of the fan in a radial direction and they tend to spread in the radial direction due to centrifugal force. In the engine room 4 of a normal size as shown in FIG. 18, the flow of the cooling air cannot go along the aforesaid vectors of the blown-off air and is disturbed as shown by the solid line arrows, and thus it does not pass smoothly, whereby back pressure occurs. The second problem is as follows. The cooling air exhaust port 12 is opened at the position where an unobstructed view of the engine 13 and the hydraulic pump 15 being the noise sources can be obtained if the opening area is increased in order to reduce the back pressure occurring due to the resistance of the cooling air exhaust port 12, and therefore the noise therefrom are directly released outside without being attenuated, thus providing less effect of reducing the ambient noise.
Hence, the art of providing the cooling air passage in which sufficient discharge of cooling air is compatible with sufficient reduction in noise release is always demanded.
As the fist prior art for solving the above problem, for example, Japanese Patent No. 2775037 discloses the art of a sound insulation housing having an inlet and discharge duct which is designed to attenuate inlet noise and exhaust noise. FIG. 20 and FIG. 21 are explanatory views of the art disclosed in the same Patent, FIG. 20 is a partially omitted fragmentary sectional top view of a hydraulic shovel to which the art of the sound insulation housing is applied, and FIG. 21 is a perspective view of a counterweight of the hydraulic shovel.
In FIG. 20, an upper revolving superstructure 32 is rotatably mounted at approximately a center of an upper portion of a base carrier 31, and a counterweight 33 is placed at a rear end portion of the upper revolving superstructure 32. In front of the counterweight 33, placed are an engine 34, a hydraulic device 35 such as a hydraulic pump, engine cooling devices such as a cooling fan 16 and a radiator 17. Further, an operator""s cab 38 is placed at a left side of a front part of the upper revolving superstructure 32, and a working machine 39 is placed at approximately a center portion thereof. It should be noted that regarding the working machine 39, only a mounting boss is illustrated. The engine 13, the hydraulic device 35, the cooling fan 16 and the radiator 17 are enclosed entirely with a closed chamber housing structure 40. The closed chamber housing structure 40 is defined by the counterweight 33, a front partition wall 48 surrounding a concave space in a plan view in front of the counterweight 33, an engine cover and a bottom plate not illustrated of a known art.
Further, as shown in FIG. 21, the counterweight 33 is formed between a panel wall 47 provided in a circumferential direction so as to be along an arc-shaped outer wall 49 with a predetermined space inside from the arc-shaped outer wall 49 of the counterweight 33 and the aforesaid arc-shaped outer wall 49. The counterweight 33 includes a exhaust duct 41 having a exhaust passage 42 for engine cooling air, and an exhaust port 43 opened downward to the outside at an end portion of the depth of the exhaust duct 41 in the circumferential direction. Further, at a right side of a front part of the upper revolving superstructure 32, an inlet passage 45 is provided for engine cooling air, and an inlet duct 44 connected to a right side of a front end portion of the counterweight 33 is placed. The inlet passage 45, the concave space in front of the counterweight 33, and the exhaust passage 42 and the exhaust port 43 define the engine cooling air passage.
Further, as a second prior art, there is a cooling device for an engine described in, for example, Japanese Utility Model No. 2548492. FIG. 22 to FIG. 24 are explanatory views of the cooling device described in the same Utility Model. FIG. 22 is a perspective view of an essential part of a hydraulic shovel including the cooling device, FIG. 23 is a partially cutaway plan view of an essential part of the hydraulic shovel including the cooling device, and FIG. 24 is a sectional view taken along the line 24xe2x80x9424 in FIG. 23.
At a rear end portion of the upper revolving superstructure 2 rotatably mounted on a top portion of the base carrier 1, placed is the counterweight 3, in front of which the engine room 4 is provided. In the engine room 4, laterally (in a left and right direction of a vehicle) placed are the engine 13, the cooling fan 16 driven by the engine 13, and the radiator 17 at an upstream of cooling air from the cooling fan 16. In a guard plate with which a top surface and left and right side surfaces of a rear portion of the upper revolving superstructure 2 are covered, provided is an air inlet port 91 opened in a top surface in front of the radiator 17. A noise suppressing duct 92 is vertically formed inside the counterweight 3, and an outlet 93 for air exhausted from the noise suppressing duct 92 is formed in a top surface of the counterweight 3. In a lower end portion of the noise suppressing duct 92, an air inlet port 97 is opened in parallel with a longitudinal direction of the engine 13 (left and right direction of the vehicle) at the front portion of the counterweight 3. Further, a noise absorbing material 96 is attached on a inner surface of the noise suppressing duct 92. When an outside air taken in from the air inlet port 91 as shown by the arrow 94 is exhausted from the noise suppressing duct 92 via the inside of the engine room 4 as shown by the arrow 95, part of the engine noise in air is designed to be absorbed in the noise absorbing material 96.
According to the above configuration, the engine room 4 is communicated with and opened to the outside via the noise suppressing duct 92. As a result, the outside air introduced by the cooling fan 16 via the radiator 17 is quickly exhausted from the engine room 4 via the noise suppressing duct 92 after cooling the engine 13 and thus it can sufficiently cools the engine room 4.
However, the above prior arts have the following disadvantages.
The art disclosed in the aforesaid Japanese Patent No. 2775037 has the following disadvantage.
In FIG. 20, the noises from the engine 34 and the hydraulic device 35 are released outside via the exhaust duct 41 placed at the back of the counterweight 33, which is highly effective at reducing noise. However, all of the cooling air for the radiator 17 has to pass the exhaust passage 42.and the exhaust port 43 inside the exhaust duct 41, whereby the back pressure of the cooling air increases and air flow decreases, thus reducing cooling efficiency.
If an outer diameter of the cooling fan 36 is set to be larger, or the rotational frequency is set to be higher in order to compensate the decrease in the air flow to prevent the engine 34 from overheating, not only the noise from the cooling fan 16 increases, but also horse power consumption increases. Increase in the horse power consumption of the cooling fan 16 results in reduction in actual output power of the engine 34 (output power usable for driving the working machine 39) and rise in fuel consumption rate per actual output power, which reduces the commercial value of the hydraulic shovel.
Further, in the embodiment of Japanese Patent No. 2775037, a small-sized rotary hydraulic excavation vehicle (so-called a small back rotary hydraulic shovel) as shown in FIG. 20 is disclosed. However, when the excavation vehicle is in a medium and large size, the engine is large, whereby a larger cooling air flow is required for the engine, and thus the disadvantage accompanying a rise in the back pressure of the aforesaid cooling air is made conspicuous. Accordingly, it is difficult to say that this structural arrangement can be generally used for small-sized to large-sized hydraulic shovels.
Next, the cooling device for the engine described in Japanese Utility Model No. 2548492 has the following disadvantage.
An outside air taken in by the cooling fan 16 is exhausted to the outside via the noise suppressing duct 92 inside the counterweight 3 after cooling the engine 13, and therefore all the air inside the engine room 4 goes to the inlet port 97 at the lower portion of the front surface of the counterweight 3. In other words, the noise suppressing duct 92 inside the counterweight 3 cools the radiator 17 as well as the engine room 4. Thus, most of the air from the cooling fan 16 collides against the partition walls on the left and right and the top and bottom of the engine room 4, and it is difficult to say that sufficient air flow exhausted from the inlet port 97 can be obtained. Specifically, it is strongly desired that a larger amount of cooling air be secured.
As described above, three needs of discharge of sufficient amount of cooling air, sufficient reduction in noise release, and reduction in size of the engine room are not eliminated and remain contradicting each other.
The present invention is made in view of the above disadvantages, and its object is to provide an engine cooling air passage for construction equipment capable of reducing noise release from a cooling air exhaust port with the back pressure of the cooling air remaining low and of making an engine room compact.
In order to attain the above object, a first configuration of an engine cooling air passage for construction equipment according to the present invention is in an engine cooling air passage for construction equipment in which an engine room enclosing an engine, a radiator and a cooling fan for cooling the radiator is adjacently placed in front of a counterweight at a rear end portion of a vehicle so that a direction of an axis of rotation of the cooling fan is in a lateral direction of the vehicle, and an outside air is taken in by the cooling fan and is discharged to an outside via an inside of the engine room, having the configuration in which a fan air diversion passage of a predetermined length, which has a fan air diversion opening located near an outer periphery portion of the cooling fan and taking in a cooling air blown by the cooling fan, at one end side, and an opening located near a lateral end portion of the counterweight and discharging the cooling air taken in to an outside, at the other end side, is formed either in a front portion of or in front of the counterweight.
The air blown by the rotation of the cooling fan normally has the property that the air speed is higher as it is farther from the fan center in the radial direction and that the it tends to spread in the radial direction by centrifugal force. Accordingly, the air at a very high speed which is blown from the outer periphery portion of the cooling fan spread outward to the engine room partition wall near the outer periphery portion of the air outlet.
According to the above first configuration, the fan air diversion opening is provided in the engine room partition wall near the outer periphery portion of the cooling fan. Thus, the high-speed cooling air from the outer periphery portion of the fan air outlet directly flows into the fan air diversion opening without resistance before cooling the engine, and flows while maintaining the high speed in a state near laminar flow by the fan air diversion passage and is exhausted to an outside from the opening at the other end side.
Accordingly, a large amount of cooling air per opening area is exhausted from the fan air diversion passage, while in the engine room, an eddy flow of the high-speed cooling air reflected at the partition walls is eliminated and the residual air flows smoothly, thus drastically reducing the back pressure of the cooling fan owing to both the effects. Consequently, even if the opening area of the cooling air exhaust port at the top surface at the downstream side of the engine room is reduced to be less than the opening area of the cooling air exhaust port according to the prior art by the opening area of the fan air diversion passage or more, the back pressure can be reduced by the same amount or less, thus making it possible to secure the same amount of engine cooling air passing the radiator or more.
As a result, the noise in the engine room is attenuated by the fan air diversion passage of a predetermined length and released outside on one hand, and it is released from the cooling air exhaust port with the drastically reduced area on the other hand, thus making it possible to drastically reduce the noise release from the engine room.
When the fan air diversion passage is formed in the front portion of the counterweight, the space for placing the diversion passage becomes unnecessary correspondingly, thus reducing the distance between the engine room and the counterweight to make it possible to reduce the engine room and construction equipment in size.
As a result, the needs of the three items: discharge of the sufficient amount of cooling air, sufficient reduction in noise release, and compact engine room: can be realized at the same time.
Further, in the engine cooling air passage for the construction equipment, the configuration in which noise absorbing materials are attached on an inner wall of the fan air diversion passage may be suitable.
According to the above configuration, since the noise passing through the fan air diversion passage contacts the noise absorbing materials over the large area, the noise in the high-frequency band is drastically attenuated by the noise absorbing materials in addition to the noise in the low-frequency band being attenuated by the diversion passage of the predetermined length itself. As a result, not only is the noise further attenuated, but it also becomes less offensive to the ear, thus making it easy to correspond to noise control.
A second configuration of an engine cooling air passage for construction equipment according to the present invention is in an engine cooling air passage for construction equipment in which an engine room enclosing an engine, a radiator and a cooling fan for cooling the radiator with a cover is provided, and an outside air is taken in by the cooling fan and is discharged to an outside via an inside of the engine room, having the configuration in which a fan air diversion duct of a predetermined length, which has a fan air diversion opening located near an outer periphery portion of the cooling fan and taking in a cooling air blown by the cooling fan, at one end side, and
an opening for discharging the cooling air taken in to the outside, at the other end side, is provided at least either one of at a side of or above the engine.
According to the above configuration, the fan air diversion opening is provided in the engine room partition wall at a side of and/or above the engine. Thereby, the high-speed cooling air from the outer periphery portion of the fan air outlet directly flows into the fan air diversion opening without resistance before cooling the engine, flows while maintaining the high-speed in a state near the laminar flow by the fan air diversion duct, and is exhausted to the outside from the opening at the other end side. Accordingly, the same operation and effects as in the case of the fan air diversion passage according to the above first configuration is obtained, and the needs in the three items of the sufficient discharge of the cooling air, sufficient reduction in noise release, and a compact engine room can be realized at the same time.
Further, an optional layout can be set such as lateral placement (an axis of rotation of the engine is placed in parallel with the lateral direction of the vehicle), vertical placement (the axis of rotation of the engine is placed in parallel with the longitudinal direction of the vehicle) and the like, and therefore the engine room according to the second configuration can be generally applicable to medium and large sized construction equipment. Above all, since the engine room according to the second configuration can be formed into approximately a rectangular parallelepiped shape, it is applicable to portable engine loaded devices such as a portable engine motor, a portable compressor and the like in which the appearance of the engine room is set by the location of the portable products. By applying the engine room to these devices, the most suitable engine loaded devices with excellent appearance and reduction in noise can be obtained.
Further, in the engine cooling air passage for the construction equipment, the configuration in which noise absorbing materials are attached on an inner wall of the fan air diversion duct may be suitable.
According to the above configuration, the same operation and effects as in the above similar configuration can be obtained. Thereby, the noise passing through the inside of the fan air diversion duct is further drastically attenuated in the high-frequency band by the noise absorbing material in addition to the attenuation in the low-frequency band by the diversion duct of a predetermined length itself. As the result, not only the noise is further attenuated, but also it becomes less offensive to the ear, thus making it easy to correspond to noise control.
Furthermore, in the engine cooling air passage for the construction equipment, the configuration in which oil pipelines an provided inside the engine room and connect an oil cooler for cooling working fluid of a hydraulic device and a working fluid tank are placed in an inner space of the fan air diversion duct.
According to the above configuration, the space for placing the piping can be reduced and the pipelines can be cooled at the same time. Specifically, as for the space for placing the piping, the pipelines are normally placed with a predetermined space being provided around them for the prevention of the interference with the vibrations caused by the pressure pulsation of inner fluid and for maintainability (easiness in individual attachment and detachment). Thus, the placement of the piping requires a space several times as large as the volume of the pipelines, which makes a large dead space. According to the above configuration, the pipelines are placed in the fan air diversion duct, whereby the aforesaid dead space is used as the passage for the fan air, and therefore the saving effect of the space is large, thus making it possible to make the construction equipment compact.
Next, as for the cooling of the pipelines, in the construction equipment such as a hydraulic shovel, the working machine, carrier, and the like are driven by hydraulic pressure, and therefore large sized oil cooler for controlling a rise in working fluid temperature has been essential so far. According to the above configuration, since the oil pipelines for connecting the oil cooler and the working fluid tank are placed inside the fan air diversion duct, they are cooled by the cooling air at the temperature almost equal to the outside temperature, which is blown from the outer periphery portion of the air outlet of the cooling fan. Thereby, the heat amount which has to be cooled by the oil cooler decreases, thus making it possible to reduce the thickness of the core of the air-cooled type of oil cooler and increase the intervals between the cooling fins under a constant amount of cooling air. Consequently, the oil cooler can be reduced in size, and the air flow of the cooling fan increases while passage resistance of the cooling air is reduced, thereby making it possible to reduce the rotational frequency of the cooling fan or reduce the cooling fan in size correspondingly, whereby consumption horse power of the cooling fan decreases. Thereby, the fuel economy of the construction equipment can be improved, and the surplus engine horse power can be used for the working machine, carrier, and the like, thus making it possible to improve operability and traveling.
As the result of the above, in addition to the same operation and effects as in the aforesaid second configuration, compact construction equipment with less fuel consumption can be realized.